Molecules 2010, 15
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of the medium and on the polymer structure. Generally, It was found that the rate of release of 5-ASA
increased as the pH increased in alkaline medium (i.e. within the colon pH). Generally, as the number
of carboxylic acid groups on monomeric units along the polymer chain increased, the hydrophilicity of
the polymer increased, and the rate of hydrolysis increased and consequently, the amount of 5-ASA
released increased. Moreover, the synthesized azo polymers showed good thermal stability and the
onset decomposition temperature of all these polymers was found to be above 195 ºC under nitrogen.
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